HP Hitachi Dynamic Link Manager Software Licenses - Manual (Page 34)

Figure 2-6 Flow of I/O Data When the Load Balancing Function Is Used
When the load balancing function is used, I/O operations are distributed via
multiple physical paths (A, B, C, and D). This helps to prevent problems with
system performance and helps prevent bottlenecks from occurring.
Paths to Which Load Balancing Is Applied
This section describes, for each type of storage system, the paths to which
the load balancing function is applied.
When Using the Thunder 9500V Series, or Hitachi AMS/WMS series
When HDLM performs load balancing, it differentiates between load balancing
among owner paths and among non-owner paths. An owner path is a path
that passes through the owner controller for a target LU. This path is set on
the owner controller of the storage system LU. Because the owner controller
varies depending on the LU, the owner path also varies depending on the LU.
A non-owner path is a path that uses a CHA other than the owner controller
(a non-owner controller). The paths to be used are selected, in the order of
owner paths and non-owner paths. To prevent performance in the entire
system from deteriorating, HDLM does not perform load balancing between
owner paths and non-owner paths. When some owner paths cannot be used
due to a problem such as a failure, load balancing is performed among the
2-12
HDLM Functions
Hitachi Dynamic Link Manager (for Solaris) User Guide